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SE Harold Street - 52nd Ave to Foster Rd

Final Project Evaluation

Introduction

The Traffic Calming Section of the Portland Office of Transportation began a project in January of 1991 to address traffic problems identified by residents along SE Harold between 52nd Avenue and 72nd Avenue. Further investigation prompted the traffic committee to expand the project to include SE Harold between 72nd Avenue and Foster Road.

The purpose of this report is to describe the measured effects the chosen devices had on the neighborhood traffic conditions.

SE Harold's Role In The Neighborhood Transportation System

SE Harold, as a Local Service Street, is intended as an access between private property and Neighborhood Collector streets. It is 36 feet wide, except for one 40-foot wide block, making it significantly wider than most nearby streets. It is the only continuous East-West street between SE 52nd Avenue and SE Foster Road, except for SE Woodstock Boulevard four blocks South. The other parallel arterial streets are SE Foster Road and SE Holgate Boulevard to the North. 52nd Avenue, 72nd Avenue, Holgate Boulevard and Woodstock Boulevard are Neighborhood Collectors, Foster is a Major City Traffic street. SE Harold's location and width served to make it an inviting traffic route. SE Harold from 52nd Avenue to Foster Road serves a mixed use residential and commercial neighborhood with Mt. Scott Park at the intersection of 72nd Avenue. This section of SE Harold also has a Tri-Met bus route and is a designated Primary Fire Response Route.

SE Harold Location Map

SE Harold's Original Traffic Conditions

SE Harold's 85th percentile speed was measured to be 37-40 miles per hour, over the length of the street, in a 30 mph zone (15% of vehicles exceed 37-40 mph).

The daily traffic volume was measured in the range of 3400 to 4800 vehicles per day (vpd). This volume of traffic is considered high for a street like SE Harold. The volume of traffic, combined with retail uses, and pedestrian generators, like the park and Tri-Met, made the excessive speeds measured there a significant concern. A large portion of the average daily traffic on SE Harold, prior to this project, was believed to be cut-through traffic.

Project Development

A traffic committee was formed from residents in the local neighborhood to decide on the best plan for meeting their project goals. Bureau of Traffic Management staff developed several alternatives for strategically locating devices to achieve the project goals.

The alternatives were presented to the traffic committee. After discussing the choices, the Committee chose Alternate 3. Of the 628 ballots mailed to eligible households 63% returned them with 69% in favor of the project.

The project speed bumps were constructed between July of 1993 and May of 1994 by the Bureau of Maintenance. The project median island and curb extensions were constructed between July and October of 1994 by Copenhagen Utilities and Construction, Inc., at a cost of approximately $117,000.00.

Project Performance

Traffic Volume

Traffic Volume on SE Harold, 52nd to Foster, prior to project construction ranged from 3400 to 4800 vehicles per day (vpd) with a steady increase in volume toward the East end of the street segment (Foster). This increase in volume is most probably due to Foster Avenue's higher classification and the fact that the closest freeway, I-205, is to the East. Traffic Volumes along the length of SE Harold before and after project construction are shown in Graph 1.

GRAPH 1

As can be seen total volumes on SE Harold have decreased into the range of 2000 to 3500 vpd. The trend of traffic volume to increase toward the East has not changed since the reasons for the increase, Foster and I-205, have also not changed. The 1600 vehicle per day (average) drop in daily traffic volume is a reduction of 37 percent. This drop presumably represents cut-through drivers who were too inconvenienced by the speed bumps. This amount of volume decrease is considered very significant. Measurements of traffic volumes on adjacent streets show an increase on the streets adjacent to SE Harold, while the total traffic volumes, including Harold, have decreased. No adjacent side streets showed an identifiable traffic volume increase exceeding allowable thresholds.

Vehicle Speed

Graphs 2 and 3, next page, show the relationship of speed and volume measured before and after the project in the east- and westbound direction, respectively. The area under each curve represents the volume of traffic and the shift of the curve to the left indicates the reduction in speeds.

GRAPH 2

GRAPH 3

The 85th percentile speed on SE Harold prior to project construction ranged between 37 and 40 mph. Measurement since speed bump construction shows an average decrease in the 85th percentile speed of 6 mph. The posted speed limit on SE Harold is 30 mph. Graphs 2 and 3 show that the peak in speeds have shifted from the range of 34-36 mph to the range of 28-30 mph. The shape of the after curve indicates a concentration of the vehicle speeds. Also, a higher percent of vehicles are now traveling below the posted speed limit.

Graphs 4 and 5 (next page) are measurements of speeds along the length of SE Harold. The graph shows the variation in speeds measured between speed bumps.

GRAPH 4

GRAPH 5

Safety and Livability

All Traffic Calming Projects share the desire to increase the safety and livability of the neighborhood and the city. Whenever the average speeds and volumes of vehicles are reduced an associated reduction in the number and severity of accidents can be anticipated. Additionally, a reduction in the speed of drivers allows them more time to observe the roadway for conflicts and permits shorter stopping distances. Fewer drivers using the street creates more and longer gaps for pedestrians to cross.

A check of available Department of Motor Vehicle records for the 15 months before the bumps were constructed as compared to the same time period after bump construction shows a drop from 17 to 13 in reported accidents. The number of injuries reported in those accidents has dropped from 16 to 8.

Conclusions

Traffic Calming on SE Harold has been very successful and neighborhood livability has been enhanced.

Speed reduction on SE Harold was effective and was typical of similar traffic calming projects. The 85th percentile speeds are 6 mph lower than the pre-project speed of 38 mph and traffic volumes were reduced 37%. Since a significant amount of traffic has been diverted from SE Harold, presumably former cut-through traffic, the remaining speeders can be assumed to be primarily local residents.

Recommendations

Follow-up velocity, volume and accident counts in four years to determine the long-term effect of the speed bumps.